Polymer-based nanocomposite materials and methods of production thereof

ABSTRACT

Polymeric-based nanocomposites with different structures using core-shell particles. The present invention provides a method for producing polymer-based core-shell nanocomposite structures. The nanocomposite materials may be produced with voids in them which may be partially or completely filled with other materials. The core and shell materials may be formed from multicomponent materials, in the case of the cores these may be for example multiple oxides, semiconductors and in the case of the polymer shell material multiple polymers in blends or copolymers.

CROSS REFERENCE TO RELATED APPLICATION

This patent application claims benefit of U.S. Provisional PatentApplication Ser. No. 60/182,749 filed on Feb. 22, 2000.

FIELD OF THE INVENTION

The present invention relates to polymer based nanocomposite materialsand their methods of production.

BACKGROUND OF THE INVENTION

In the recent decade, polymer-based nanocomposite materials haveattracted a great deal of attention because of their applications invarious high-tech applications, such as micromechanical devices, memorystorage media, chemical and biochemical sensors, display devices, andphotonic band-gap materials. Generally, colloid crystals are employedeither as templates for producing ordered 2D or 3D structures, (Holland,B T, Blanford, C F, Stein A. Science 1998, 281, 538; Zahidov, A. A. etal. Science 1998, 282, 897; Wijnhoven, J. E. G., Vos, W. L. Science1998, 281, 802; Lenzmann, F., Li, K., Kitai, A. H., Stöver Chem. Mater.1994, 6, 156) for example, in the fabrication of photonic bang gapmaterials or on their own right as chemical sensors (Holtz, J. H.,Asher, S. A. Nature 1997, 389, 829) and devices for memory storage(Kumacheva, E.; O. Kalinina; Lilge, L. Adv. Mat. 1999, 11, 231).

Recently, a new approach to producing 3D polymer-based nanocompositeshas been proposed. This method employs latex particles composed of hardcores and somewhat softer shells (Kalinina, O.; Kumacheva. E.Macromolecules 1999, 32, 4122). U.S. Pat. No. 5,952,131 to Kumacheva etal., the contents of which are incorporated herein by reference,discloses a material having a matrix composed of particles having a coreresin and a shell resin. FIG. 1 a demonstrates the stages in fabricationof such a nanocomposite material from core-shell latex particles.Core-shell latex particles, composed of hard cores and somewhat softershells, are synthesized at step A. The particles are packed in a closepacked array, at step B, and annealed at step C at the temperature thatis above the glass transition temperature, T_(g), of the shell-formingpolymer (SFP) and below the T_(g) of the core-forming polymer (CFP). Asa result, the latex shells flow and form a matrix, whereas the rigidcores form a disperse phase.

With this approach, it is known to incorporate functional componentsinto the CFP. When the diffusion of the functional component between thecores and the shells is sufficiently suppressed, nanocomposite materialswith a periodic modulation in composition are produced. It is also knownto prepare materials with a direct structure in which fluorescent coreparticles are embedded into an optically inert matrix.

It would be very advantageous to be able to produce a nanocompositetemplate array that would enable one to incorporate a wide array ofmaterials, either organic or inorganic based materials into the templateand to facilitate a method of rapidly and economically producing a broadrange of polymer-based nanocomposites with periodic modulations incomposition and properties. Such materials would have applications inmemory storage, photonic crystals, micromechanical actuators, devicesfor telecommunications, interference and high-refractive index coatings,bio- and chemical sensors.

SUMMARY OF THE INVENTION

The present invention provides a method for producing polymer-basedcore-shell nanocomposite structures with numerous combinations ofproperties of the constituent particles and the matrix.

The present invention provides polymer-based nanocomposites obtained bysynthesizing core-shell particles with organic or inorganic cores andpolymeric shells; arranging them in one-, two-, or three-dimensionalarrays, and annealing them at the temperature at which polymeric shellsflow.

The present invention provides a nanocomposite material, comprising;

a plurality of rigid core particles embedded in a polymeric material andincluding air voids located in said polymeric material.

The rigid core particles and the soft polymeric shells may have asingle-component or a multicomponent structure providing a route tomulticomponent nanocomposite materials.

The present invention also provides a nanocomposite material,comprising;

a plurality of rigid core particles embedded in a polymeric material,said rigid core particles comprising multicomponent organic or inorganicmaterials.

The present invention also demonstrates that the ratio between thedimensions of the particle cores and shells can be manipulated toproduce a material containing voids that may be filled with variousspecies.

In another aspect of the present invention there is provided a method ofsynthesizing a nanocomposite material, comprising;

coating a plurality of rigid substantially spherical core particles witha polymeric shell material, said core particles having a radius r_(c)and said polymeric shell material coating said core particles having athickness I_(s), selecting the radius r_(c) of the rigid spherical coreparticles and the shell thickness I_(s) to satisfy 0.05<I_(s)r_(c)<0.2,said polymeric material having a glass transition temperature above roomtemperature, the rigid core particles having softening temperaturegreater than a softening temperature of said polymeric material suchthat upon annealing the polymeric material softens and flows while therigid core remains solid;

producing one of a one-dimensional, two-dimensional andthree-dimensional array with the coated rigid core particles; and

heating said array above the softening temperature of the polymericmaterial at which it flows to form a continuous phase having air voidsdispersed therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

The method of producing polymer-based core-shell nanocompositestructures according to the present invention, will now be described, byway of example only, reference being had to the accompanying drawings,in which:

FIG. 1 a is a diagrammatic representation of a Prior Art method offormation of polymer-based nanocomposite material, stage A: synthesis ofthe core-shell particles with hard cores and soft shells, stage B:assembly of particles in a 1D, 2D, or 3D close-packed structure, stageC: heat treatment of the particle compact that leads to flow of softshells and formation of a nanocomposite polymer;

FIG. 1 b is a diagrammatic representation of a portion of steps B and Cof FIG. 1 a the prior art method of formation of polymer-basednanocomposite material using a thick polymeric shell that ensures acontinuous void-free core-shell composite material;

FIG. 2 shows the principle of the preparation of a nanocompositematerial containing voids in accordance with the present invention;

FIG. 3 shows a laser confocal fluorescent microscopy image of thenanocomposite material containing voids, the scale bar is 2 μm, the sizeof the fluorescent poly (methyl methacrylate) core particles is 0.5 μm,the thickness of the poly (methyl methacrylate)—poly (butylmethacrylate) shells is 0.08 μm;

FIG. 4 is an Atomic Force Microscopy image of the nanocomposite materialformed from the core-shell particles with conductive polypyrrol coresand poly (butyl acrylate) shells;

FIG. 5 shows polypyrole cores covered with poly (butyl methacrylate)(PBMA) particles;

FIG. 6 shows core-shell polypyrrole-poly (butyl methacrylate) particlesize as a function of the ratio between the weight concentration of thecore- and shell-forming particles;

FIG. 7 shows the polydispersity of the core-shell polypyrrole-poly(butyl methacrylate) particles as a function of the ratio between theweight concentration of the core- and shell-forming particles;

FIG. 8 is an Atomic Force Microscopy image of the nanocomposite materialformed from the core-shell particles containing silica cores and poly(methyl methacrylate) shells, the size of silica particles is 0.6 μm;

FIG. 9 is a diagrammatic representation of a method of producingmultilayer cores by using silica particles as templates and attachingtitanyl sulfate or titanium oxide coating to the core particles;

FIG. 10 shows the mass ratio TiO₂/SiO₂ in the core shell particles as afunction of ratio TiOSO₄/surface area of SiO₂, squares are thecalculated ratio, diamonds are the experimental results obtained byelemental analysis;

FIG. 11 shows the structure of SiO₂ particles as a function of theweight concentration of titanyl sulfate in dispersion;

FIG. 12 is a Scanning Electron Microscopy image of the silica particles(a) and silica particles coated with TiO₂ shells (b), the size of silicaparticles is 580 nm, the diameter of the SiO₂—TiO₂ particles is 0.78 μm;

FIG. 13 is an Atomic Force Microscopy image of the nanocompositematerial formed from the core-shell particles with SiO₂—TiO₂ cores andpoly (methyl methacrylate) shells; and

FIG. 14 shows Bragg diffraction patterns of the films formed from thecore-shell particles with SiO₂—TiO₂ cores and poly (methyl methacrylate)shells.

DETAILED DESCRIPTION OF THE INVENTION

The present invention describes a process for producing polymer-basedcore-shell nanocomposite structures. Particularly, the inventionprovides core-shell nanocomposite structures having periodic voidsdispersed throughout the structure. The invention also providescore-shell nanocomposite structures in which the cores comprisemulti-component constituents in which the differing constituents maycover the ambit of both organic and inorganic materials and thesestructures are produced both with and without periodic voids dispersedthroughout the material.

The schematics of the approach for growing a polymer-based nanocompositewith a continuous core-shell structure is shown in FIG 1 a. As discussedin the introduction, stage A involves the synthesis of the core-shelllatex particles that consist of a hard core and a somewhat softer shell.The materials chosen for the synthesis of the core and shell materialsmust satisfy two important requirements. First, the temperature ofsoftening of the core-forming material (CFM) and the shell-formingpolymer (SFM) should be such that upon annealing the SFM softens andflows while the CFM remains intact. Second, the shell-forming materialmust have the glass transition temperature well above the roomtemperature. Any possible diffusion of species between the core and theshell during synthesis or during annealing should be suppressed to givea distinct or abrupt well defined boundary between the core and shell.

Several non-limiting and purely exemplary examples are given below todemonstrate different combinations of materials incorporated into thecore- or shell-forming polymers.

EXAMPLE 1

Formation of the Nanocomposite Material with Voids Available for FurtherIncorporation of Functional Species

The principle of tuning of the structure of the nanocomposite materialto incorporate periodic voids is shown in FIG. 2. The ratios between thevolume fractions of the CFM and the SFM leading to formation of thenanocomposite material with voids is shown in Table 1 in a shadowed areawhile the fractions outside of the shadowed section of the Table give acontinuous structure. To form a homogeneous matrix the ratio between thethickness of the shell, I_(s), and the radius of the core (r_(c)) shouldexceed 0.2, i.e., I_(s)/r_(c)<0.2. When 0.05<I_(s)/r_(c)<0.2, the amountof the CFM is not sufficient to form a continuous matrix and small voidsare left between particles. The recipe of one embodiment of a synthesisof the core-shell particles with fluorescent polymeric cores andoptically inert polymeric shells leading to this type of structure isgiven in Table 2. It is evident from FIG. 2 that the composite structurecomprises voids 22 periodically dispersed throughout the material. FIG.3 shows a laser confocal fluorescent microscopy image of a nanocompositematerial containing voids in which both the core and shell are polymermaterials. Fluorescent cores appear as bright domains, whereas blackdomains correspond to air voids available for filing them with differentpolymer or inorganic materials using electrochemical approaches, vacuumdeposition, or capillary infiltration with liquid phases. The size ofthe fluorescent poly (methyl methacrylate) core particles is 0.5 μm, thethickness of the poly (methyl methacrylate)-poly (butyl methacrylate)shells is 0.08 μm. The scale bar is 2 μm.

The cores may be formed of organic. e.g. polymeric materials orinorganic materials including oxides such as TiO₂, SiO₂ and the like. Atthe assembly state analogous to stage B in FIG. 1 a (but with theappropriate core-shell ratios to give periodic voids) the core-shellparticles are arranged in a one-dimensional, two-dimensional, orthree-dimensional array by using sedimentation, electrodeposition orcentrifugation. Fabrication of the composite material is completed byannealing of the dry compact (analogous to stage C in FIG. 1 a). At thisstage, the composite material is heated above the softening point of theSFM, at which it flows and fills partly or completely voids between thecore particles and forms a continuous phase. In this approach, the SFMshould be such that the shells possess enough elasticity to act as abarrier to prevent the aggregation of the cores.

The present method disclosed herein provides several levels of controlof the structure and function of the nanocomposite. First, the diametersof the cores and the thicknesses of the shells may be varied andcontrolled leading to the variation in particle size and number densityin the nanocomposite material. Secondly, the shape of the core-shellparticles i.e. spherical shape versus a rod-like shape, can bemanipulated at stage A. Third, the suggested approach provides severaltypes of morphologies of the ultimate composite material. When theshells are sufficiently thick, the SFM fills gaps between the coreparticles, i.e., forms a continuous matrix. For thin shells, the rigidparticles are just “glued” together by the SFM. In this way compositematerials are formed, in which small voids between particles can befilled with another functional material. Finally, the composition of theCFM and the SFM can be varied and controlled in a variety of ways,several of which will be described below.

The core-shell particles can be monodispersed or polydispersed dependingon a desired application of the nanocomposite material. To formnanocomposites with ordered structures, the core particles preferablyare monodisperse, the shells are preferably uniform in thickness, andthe entire core-shell particles are monodispersed. The CFM may be eithera single or multicomponent material. In the multicomponent cores,several species can form distinct layers or can be mixed to form ahomogeneous phase. The multicomponent materials may be inorganic basedmaterials e.g. oxides, or multicomponent organic materials, e.g. polymermixtures, blends and the like.

The structure of the nanostructured material with necks betweenmonodispersed colloid particles and voids between the particles issimilar to the structure of templates used for producing photonic bandgap materials, (REF) but has a much better processibility (e.g. it canbe polished) and resistance to cracking. Due to the presence of voidsand ordered structure the material appears as highly irridiscent, andcan be used as diffraction coating or free-standing film. Alternatively,the voids may be filled with photosensitive materials such as dyes orchromophores. For example, a monomer covalently labeled or mixed with afluorescent dye with the absorption peak similar or different then theabsorption peaks of the dye(s) incorporated in the core and/orcore-forming polymer may be used for several applications including datastorage media. Under imaging of the structure different materialmorphologies will be observed for different wavelengths of irradiation.Local photobleaching of a particular dye in the specific lateral orvertical plane will enable one to incorporate a secret code in thincoating for security needs.

Alternatively, inorganic, e.g. semiconductor particles may beincorporated into the voids using capillary flow, infiltration or vacuumdeposition. First, upon dissolution of the particles, octahedralnanostructures will be obtained which have a very high control overtheir dimensions and monodispersity. Second infiltration of a monomer ora polymer mixed with inorganic material, having nonlinear propertieswill lead to the periodic modulation of optical properties of thematerial.

EXAMPLE 2

Polymer-based Nanocomposite Material Formed from Core-shell Particleswith Electroconductive Polymer and Dielectric Shells

Conductive monodisperse polypyrrole particles with the dimensionsvarying 0.08 to 300 μm covered with the dielectric poly (butylacryalate) shells were synthesized using the recipe given in Table 3. Afilm formed from polypyrrol particles showed a finite conductivity. Whenan elastomeric layer comprised of a cross-linked poly (butyl acrylate)was attached to the core particles, a film formed by annealing of thesediment formed by the core-shell particles showed conductivitydepending on the thickness of the elastomeric shells. Very smallstretching of the film led to significant drop in conductivity. Thesefilms can be used for non-destructive control of strains in variousmaterials or be incorporated in micromechanical devices in whichthorough control of small displacements is required. FIG. 4 is an AtomicForce Microscopy image of the nanocomposite material formed from thecore-shell particles with conductive polypyrrol cores and poly (butylacrylate) shells.

The polymeric CFM can be represented by a pure polymer or a polymerwhich is functionalized by either chemically attached functional groupsor mixing it with appropriate low or high-molecular weight species. Whenthe core-shell particles are made from dissimilar materials and theaffinity between the core and the shell material is not sufficient toprovide adhesion between the cores and the shells, interfacialpolymerization is not efficient and the shell-forming polymer was foundto nucleate and polymerize in the bulk rather that on the surface of thecore particles. In this situation, the attachment of shells was providedby electrostatic attraction between cores and shell-forming particlessynthesized from materials carrying opposite charges, as is shown inFIG. 5. After attachment the shell-forming polymer was annealed to forma dense and uniform shell, which could be later transformed into amatrix.

The amount of the shell-forming polymer to the core-forming polymer hadto provide a dense coverage of the core particles with at least amonolayer of the shell-forming particles. As is shown in FIGS. 6 and 7,only under these conditions core-shell particles with the well-definedsize and high monodispersity could be produced after coating the coreparticles.

EXAMPLE 3

Polymer Nanocomposites Formed by Inorganic Particles Embedded in aPolymeric Matrix

Monodispersed silica particles were synthesized using a recipe shown inTable 4. Poly (methyl methacrylate) shell was attached to the silicaparticles, and a sediment of the core-shell particles was heated at thetemperature leading to flow of PMMA. FIG. 8 shows an Atomic ForceMicroscopy image of the nanocomposite material formed from thecore-shell particles containing silica cores and poly (methylmethacrylate) shells. The size of silica particles is 0.6 μm.

EXAMPLE 4

Polymer Nanocomposites Formed by Multicomponent Inorganic ParticlesEmbedded in a Polymeric Matrix

Multilayer cores could be produced by using silica particles astemplates and attaching titanyl sulfate or titanium oxide coating to thecore particles, as is shown in FIG. 9. Monodispersed silica particleswere synthesized using a recipe shown in Table 4. A titanium oxide layerwas synthesized on the top of silica particles using a recipe shown inTable 5. In general, the volume of TiO₂ varied from 0.05 to 0.4 withrespect to the volume of the silica particles. Referring to FIG. 10, avery important requirement in the preparation of monodispersed bilayerinorganic cores is the exact ratio between the surface area of silicaparticles and the amount of titanyl sulfate added to silica dispersion.FIG. 10 shows the mass ratio TiO₂/SiO₂ in the core shell particles as afunction of ratio TiOSO₄/surface area of SiO₂. Squares: calculatedratio; diamonds. The experimental results were obtained by elementalanalysis. The surface area of silica particles in the system wascontrolled by either silica particle size, or by their concentration inthe dispersion. Referring to FIG. 11 shows the structure of the silicaparticles (FIG. 11 a) and coated silica particles when titanyl sulfateis deficient (FIG. 11 b), in optimum ratio (FIGS. 11 c and d), and inexcess, (FIG. 11 f). FIG. 12 is a Scanning Electron Microscopy image ofthe silica particles (a) and silica particles coated with TiO₂ shells(b). The size of silica particles is 580 nm, the diameter of theSiO₂—TiO₂ particles is 0.78 μm. FIG. 13 shows an Atomic Force Microscopyimage of the nanocomposite material formed from the core-shell particleswith SiO₂—TiO₂ cores and poly (methyl methacrylate) shells. Films formedin this manner, showed strong Bragg diffraction patterns, specifically,FIG. 8 shows Bragg diffraction patterns of the films formed from thecore-shell particles with SiO₂—TiO₂ cores and poly (methyl methacrylate)shells.

In such films, the position of the diffraction peak strictly depends onthe dimensions of the cores and shells, therefore such films can be usedas interference high-refractive index polymer-based coatings for, e.g.security paper. Alternatively, the inorganic particles can be obtainedfrom semiconductors e.g. CdS—CdSe and then coated with a polymericshell. Upon annealing the quantum dots will be incorporated in thepolymeric matrix (quantum dots). Materials exhibiting electroactivitymay be incorporated into the voids.

The multicomponent materials of which the cores and/or shells areproduced may comprise two or more different materials. For example thecores may be made of two or more several different oxide materials, inlayers or a homogenous mixed oxide. The same applies to the polymericshell materials, the multicomponent shells may be made of two or morepolymers in blends, block copolymers and the like.

The foregoing description of the preferred embodiments of the inventionhas been presented to illustrate the principles of the invention and notto limit the invention to the particular embodiment illustrated. It isintended that the scope of the invention be defined by all of theembodiments encompassed within the following claims and theirequivalents.

TABLE 1 Volume Fraction of the CFP in the Polymer Nanocomposite Formedfrom Core-Shell Particles with the Different Core Diameter and ShellThickness. L_(s) = r_(p) − R_(c), μm r_(c), μm 0.15 0.20 0.25 0.30 0.350.40 0.45 0.50 0.60 0.025 42 52 58 63 67 70 73 75 79 0.050 22 30 36 4247 51 55 58 63 0.075 12 19 24 30 34 38 42 46 51 0.100 8 12 17 22 26 3033 36 42 0.125 5 9 12 16 20 23 26 30 35 0.150 4 6 9 13 16 19 22 24 300.175 3 5 7 10 12 15 18 20 25 0.20 2 4 6 8 10 12 15 17 22 0.25 1 2 4 5 79 10 11 18

TABLE 2 Recipe for the Three-Stage Emulsion Polymerization of the 1050nm Core-Shell Latex Particles Stage 1 Stage 2 Stage 3 Precharge:Deionized water, g 70 70 40 Seeds from previous step, g — 20 20Potassium persulfate, g 0.2 — — AIBN, g — 0.005 0.005 Pumping mixture:MMA, g 30 7 2 BMA, g — — 1 DDM, g 0.088 0.052 0.136 EGDMA, g 1.068 0.032— NBD-MMA, g 0.01 0.0035 — AIBN, g — 0.052 0.186 Ionic initiatorsolution added simul- taneously with the monomer mixture: Potassiumpersulfate, g — — 0.0026 Water, g — — 2.6 Particle size, nm 500 640 745

TABLE 3 Recipe for the synthesis of the core-shell particles withconductive cores and dielectric shells Pyrrole, FeCl₃ Stabilizer* H₂Obutyl acrylate DDM K₂S₂O₄ Ml g g ml ml g g 0.3–1.0 5.47 0.3–1.0 100 20.13 0.1 *Hydroxy propyl cellulose, poly (ethylene oxide), poly (vinylalcohol)

TABLE 4 Recipe for the synthesis of the SiO₂ Tetraethyl TotalOrthosilicate, % volume, Reaction Particle ml Ethanol H₂O % NH₃ ml Timesize 20 234 14.4 0.84 300 3 hr 580 nm 20 234 13.8 1.4 300 1 hr 340 nm 20234 10.25 0.63 285 6 hr 120 nm

TABLE 5 Recipe for the synthesis of the SiO₂—TiO₂ particles Silicaparticles, Volume 0.2 M Total with the diameter, Silica solid TiOSO₄ inreaction, Particle nm content, % 1M H₂SO₄ ml volume, ml size nm 220 3.025 225 260 220 0.8 100 400 1000 580 1.0 40 440 780

1. A nanocomposite material, comprising; a plurality of rigid coreparticles embedded in a polymeric shell material and including aplurality of voids located therein, said core particles having a radiusr_(c) and said polymeric shell material coating said core particleshaving a shell thickness l_(s), selecting the radius r_(c) of the rigidspherical core particles and the shell thickness l_(s) to satisfy0.05<l_(s/)r_(c)<0.2.
 2. The nanocomposite material according to claim 1wherein said core particles and said air voids are periodically disposedthroughout said polymeric shell material.
 3. The nanocomposite materialaccording to claim 1 wherein said rigid core particles are substantiallyspherical particles.
 4. The nanocomposite material according to claim 1wherein said rigid core particles comprise multicomponent organic orinorganic materials or single-component materials.
 5. The nanocompositematerial according to claim 1 wherein said polymeric shell materialcomprises multicomponent or single-component polymers.
 6. Thenanocomposite material according to claim 1 wherein said voids arepartially or completely filled with a functional material.
 7. Thenanocomposite material according to claim 6 wherein the functionalmaterial is selected from the group consisting of conducting materials,semiconductors, dielectrics, magnetic materials, polymeric materials,optically-sensitive materials and liquid crystal materials.
 8. Thenanocomposite material according to claim 1 wherein said rigid coreparticles include an electroconductive polymer and wherein saidpolymeric material includes a dielectric polymer.
 9. The nanocompositematerial according to claim 8 wherein said electroconductive polymercomprises electroconductive polypyrrole, and wherein said dielectricpolymer comprises cross-linked poly (butyl methacrylate).
 10. Thenanocomposite material according to claim 8 wherein said rigid coreparticles comprise multicomponent inorganic oxide spheres.
 11. Thenanocomposite material according to claim 1 wherein said rigid coreparticles comprise multicomponent oxide spheres.
 12. The nanocompositematerial according to claim 11 wherein said multicomponent oxide sphereseach include a silica sphere coated with another oxide shell.
 13. Thenanocomposite material according to claim 12 wherein said other oxideforming said oxide shell is TiO₂.
 14. The nanocomposite materialaccording to claim 11 wherein said polymer shell material is poly(methyl methacrylate).
 15. The nanocomposite material according to claim7 wherein said optically-sensitive material is a fluorescent dye orchromophore that fluoresces at a first wavelength, including a secondfluorescent dye or chromophore that fluoresces at a second wavelengthincorporated into said polymeric shell material, and including a thirdfluorescent dye or chromophore that fluoresces at a third wavelengthincorporated into, or bound to, said core particles.
 16. Thenanocomposite material according to claim 4 wherein said multicomponentcore includes two different components.
 17. The nanocomposite materialaccording to claim 4 wherein said multicomponent core includes three ormore different components.
 18. A nanocomposite material, comprising; aplurality of rigid core particles embedded in a polymeric shell materialand including a plurality of voids located therein, said rigid coreparticles comprising multicomponent organic or inorganic materials, saidcore particles having a radius r_(c) and said polymeric shell materialcoating said core particles having a thickness l_(s), selecting theradius r_(c) of the rigid spherical core particles and the shellthickness l_(s) to satisfy 0.05<l_(s/)r_(c)<0.2.
 19. The nanocompositematerial according to claim 18 wherein said core particles and saidvoids are periodically disposed throughout said polymeric shellmaterial.
 20. The nanocomposite material according to claim 18 whereinsaid rigid core particles comprise multicomponent organic materials ormulticomponent inorganic materials, or a combination of organic andinorganic materials.
 21. The nanocomposite material according to claim19 wherein said polymeric shell material comprises multicomponent orsingle-component polymers.
 22. The nanocomposite material according toclaim 18 wherein said voids are partially or completely filled with afunctional material.
 23. The nanocomposite material according to claim21 wherein the functional material is selected from the group consistingof conducting materials, semiconductors, dielectrics, magneticmaterials, polymeric materials, optically-sensitive materials and liquidcrystal materials.
 24. A method of synthesizing a nanocomposite materialhaving voids, comprising; coating a plurality of core particles with apolymeric shell material, said core particles having a radius r_(c) andsaid polymeric shell material coating said core particles having a shellthickness l_(s), selecting the radius r_(c) of the core particles andthe shell thickness l_(s) to satisfy 0.05<l_(s/)r_(c)<0.2, saidpolymeric shell material having a glass transition temperature aboveroom temperature, the core particles having softening temperaturegreater than a softening temperature of said polymeric shell materialsuch that upon annealing the polymeric shell material softens and flowswhile the core remains solid; producing one of a one-dimensional,two-dimensional and three-dimensional array with the coated coreparticles; and heating said array above the softening temperature of thepolymeric shell material at which it flows to form a continuous phasehaving air voids dispersed therethrough.
 25. The method according toclaim 24 wherein said array is grown using sedimentation,electrodeposition, centrifugation, or water filtration.
 26. Thenanocomposite material according to claim 24 wherein said core comprisesmulticomponent organic or inorganic materials or single-componentmaterials.
 27. The nanocomposite material according to claim 24 whereinsaid polymeric shell material comprises multicomponent orsingle-component polymers.
 28. The method according to claim 24 whereina functional material is infiltrated into said voids.
 29. The methodaccording to claim 28 wherein said functional materials is infiltratedinto said voids by one of capillary infiltration, diffusion,electrochemical deposition and vacuum vapor deposition.
 30. Thenanocomposite material according to claim 1 wherein said core particleshave an aspect ratio greater than unity.
 31. The nanocomposite materialaccording to claim 24 wherein said core particles are substantiallyspherical particles.
 32. The nanocomposite material according to claim24 wherein said core particles have an aspect ratio greater than unity.33. A nanocomposite material comprising a plurality of core particlesembedded in a polymeric material and including a plurality of voidslocated therein, produced by a method comprising the steps of: coating aplurality of rigid core particles with a polymeric shell material, saidcore particles having a radius r_(c) and said polymeric shell materialcoating said core particles having a shell thickness l_(s), selectingthe radius r_(c) of the rigid core particles and the shell thicknessl_(s) to satisfy 0.05<l_(s/)r_(c)<0.2, said polymeric shell materialhaving a glass transition temperature above room temperature, the rigidcore particles having softening temperature greater than a softeningtemperature of said polymeric shell material such that upon annealingthe polymeric shell material softens and flows while the rigid coreremains solid; producing one of a one-dimensional, two-dimensional andthree-dimensional array with the coated rigid core particles; andheating said array above the softening temperature of the polymericmaterial at which it flows to form a continuous phase having air voidsdispersed therethrough.
 34. The nanocomposite material according toclaim 33 wherein said rigid core particles are substantially sphericalparticles.
 35. The nanocomposite material according to claim 33 whereinsaid rigid core particles have an aspect ratio greater than unity. 36.The nanocomposite material according to claim 33 wherein said array isgrown using sedimentation, electrodeposition, centrifugation, or waterfiltration.
 37. The nanocomposite material according to claim 33 whereinsaid rigid core comprises multicomponent organic or inorganic materialsor single-component materials.
 38. The nanocomposite material accordingto claim 33 wherein said polymeric shell comprises multicomponent orsingle-component polymers.
 39. The nanocomposite material according toclaim 33 wherein a functional material is infiltrated into said voids.40. The nanocomposite according to claim 39 wherein said functionalmaterial is infiltrated into said voids by one of capillaryinfiltration, diffusion, electrochemical deposition and vacuum vapordeposition.